Immobilizer circuit

ABSTRACT

An immobilizer device is configured for communicating with a base station. The immobilizer device includes an antenna circuit including three orthogonally-oriented antennas configured to receive a signal from a field generated by a base station. A power circuit is configured to draw power via the field on each of the antennas, and a communications circuit is configured to communicate with the base station via any of the antennas. The strength of the signals received via the antennas is evaluated and used to select one of the antennas for use in data communications and, if appropriate, as a power supply.

Aspects of various embodiments of the present invention are directed towireless communications, and particular aspects are directed to wirelesscommunications for both power and data transmission.

Many wireless communication systems employ transponders and basestations that communicate with one another. One type of transponder usedin many applications is an immobilizer type of transponder. Generally,immobilizers use a coil that can be aligned with an antenna at the basestation along an axis to achieve coupling. This coupling is used tocontrol the operation of a circuit at a base station with which thetransponder communicates, such as to immobilize an automobile ignitionin absence of coupling with the coil (e.g., with the coil implemented ina key fob).

In many immobilizer systems, such as a vehicle ignition system, theimmobilizer needs to be oriented in a particular manner in order tocommunicate with the base station portion of the system. For instance,most applications use cylindrical coils (antennas), one for the basestation and one for the immobilizer. The coupling between the twoantennas is strongly dependent on the orientation, and the maximumcoupling can be achieved if both antennas are kept on the same axis(coaxial operation). If the base station antenna area is much largerthan the transponder antenna, real coaxial operation is not necessarilyneeded, but the axis of the transponder antenna is desirably held closeto a center axis of the base station antenna. These approaches are oftenlimited to applications with a very small angular deviation and acorrespondingly small dihedral angle, in a range of a few millimeters.Some approaches to achieving this orientation involves the physicalplacement of the immobilizer (and related housing and other components)into a physical apparatus or slot that aligns the immobilizer with thebase station. For instance, with many automobile immobilizerapplications, the immobilizer works via insertion into a slot thatensures that the immobilizer is correctly oriented relative to the basestation.

Unfortunately, such alignment systems can be difficult to use, expensiveto implement and otherwise limit the ability to readily implementtransponder-based operations. For instance, free hand operation in whichthe car key fob is kept in hand or on a user's person has been limited,generally requiring that the user ensure that the fob is positionedcorrectly and is otherwise appropriately aligned. Regarding vehicularignition operation, such systems can be particularly challenging toimplement in a manner that permits secure operation while also ensuringoperability in the event of power loss on the transponder.

These and other matters have presented challenges to the design andimplementation of immobilizer systems for a variety of applications.

Various example embodiments are directed to immobilizer devices andtheir implementation.

According to an example embodiment, an immobilizer device communicateswith a base station for operation of a circuit connected to the basestation. The immobilizer device includes an antenna circuit, a wirelesspower circuit, a communications circuit and a logic circuit. The antennacircuit includes three antennas orthogonally-oriented relative to oneanother, each antenna being configured to receive wireless transmissionsfrom a remote base station. The wireless power circuit is connected tothe antenna circuit and configured to provide power using signalsreceived from the base station via at least one of the three antennas.The communications circuit is powered by the wireless power circuit, isconnected to the antenna circuit and generates signals corresponding tothe received wireless transmissions on each of the antennas. Thecommunications circuit further provides data communications receivedfrom the base station via at least one of the channels (e.g., to thelogic circuit), and transmits data (e.g., from and/or at the directionof the logic circuit) to the base station via an antenna correspondingto one of the channels. The logic circuit processes data communicationson at least one of the channels, and to generate a data communicationfor transmission to the base station using the communications circuitand the one of the antennas corresponding to the at least one of thechannels.

Another example embodiment is directed to an immobilizer key fob devicefor communicating with a base station for an automobile ignitioncircuit. Such an ignition circuit uses data from the immobilizer tooperate (e.g., without a communication from the immobilizer, theignition circuit will not start the vehicle). The immobilizer key fobdevice includes an antenna circuit having three orthogonally-orientedantennas that respectively generate input signals on three differentantenna channels, and that align with a field generated by asingle-antenna in the base station for receiving RF communications fromthe base station. A power circuit generates a supply voltage using aninput radio frequency (RF) signal received from the base station on atleast one of the antennas. Demodulator and modulator circuitsrespectively demodulate a signal on one of the channels based upon thestrength of the signal, and modulate a carrier signal for datatransmission back to the base station. A memory circuit storesauthentication data and program data that is used by a logic circuit,which executes the program data to process data received via thedemodulated signal. The logic circuit also generates output data forcommunication back to the base station via the modulator circuit andantennal circuit, using the stored authentication data.

Another example embodiment is directed to a method for communicatingwith a remote base station using RF power. An antenna circuit havingthree antennas orthogonally-oriented relative to one another is used toreceive wireless transmissions from the base station. The wirelesstransmissions received on the antenna circuit are used to generate powerthat is used to power a logic circuit. Signals corresponding to thereceived wireless transmissions on each of the antennas are generated,and each generated signal is provided on a channel corresponding to theantenna from which the signal was generated. Data communicationsreceived from the base station are provided via at least one of thechannels to the logic circuit. In the logic circuit, data communicationsreceived on at least one of the channels is processed, and a datacommunication is generated for transmission to the base station usingthe communications circuit and the one of the antennas corresponding tothe at least one of the channels. The generated data communication istransmitted to the base station via an antenna corresponding to one ofthe channels, and may be used, for example, to enable an ignitioncircuit for a vehicle.

The above discussion/summary is not intended to describe each embodimentor every implementation of the present disclosure. The figures anddetailed description that follow also exemplify various embodiments.

Various example embodiments may be more completely understood inconsideration of the following detailed description in connection withthe accompanying drawings, in which:

FIG. 1 shows an immobilizer and immobilizer system, in accordance withan example embodiment of the present invention;

FIG. 2 shows an immobilizer and immobilizer system with a representedthree-dimensional antenna system, in accordance with another exampleembodiment of the present invention;

FIG. 3 shows an immobilizer circuit, in accordance with another exampleembodiment of the present invention; and

FIG. 4 shows another immobilizer and immobilizer system with anotherthree-dimensional antenna system, in accordance with another exampleembodiment of the present invention.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular embodiments described. On the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe scope of the invention including aspects defined in the claims. Theterm “example” as used throughout this application is only by way ofillustration, and not limitation.

Aspects of the present invention are believed to be applicable to avariety of different types of devices, systems and arrangements forwireless communications involving transponder-base station coupling,including those involving immobilizer functions. While the presentinvention is not necessarily so limited, various aspects of theinvention may be appreciated through a discussion of examples using thiscontext.

Various example embodiments are directed to an immobilizer thataddresses challenges, such as those identified in the background above.Other embodiments are directed to transponder-base station systems,which similarly address these and other challenges. In one embodiment, atransponder includes an arrangement of antennas that are configured tooperate independently from a particular axis of orientation between thetransponder and a base station and, in some implementations, to operateindependently from any orientation of the transponder. In variouscontexts, the transponder is configured to operate independently fromany need to insert the transponder, or a fob including the transponder,into a slot or other physical alignment arrangement in order to operate.

In accordance with various example embodiments, a transponder such asdescribed above is further configured for operation using power suppliedby an electromagnetic field (hereafter also “field”) generated at thebase station. The transponder is configured with antennas that areconfigured to facilitate both data transmission and energy transfer withthe base station, independently from the orientation of the transponderrelative to a field generated by the base station. One or more of theantennas receive data and/or power (via the field) generated by the basestation, and further communicate a response back to the base station. Awireless power circuit at the transponder is used to generate power thatthe transponder uses for communications.

In a more particular example embodiment, an immobilizer device includesa transponder having a plurality of orthogonally-arranged antennas thatfacilitate communication and wireless energy transfer with a basestation, in a manner that is generally independent from the orientationof the immobilizer device relative to the base station. In this contextand as otherwise described herein, the terms orthogonally-arranged ororthogonal refer to antennas that are generally, though not necessarilyprecisely, orthogonal relative to one another. The antennas may be aboutorthogonal, or within a few degrees of orthogonal, or within about 20degrees of orthogonal.

In one implementation, the immobilizer device includes threeorthogonally-arranged antennas configured to operate for both data andpower communication in a field generated by the base station, and forimmobilizing functions relative to the activation (or lack thereof) ofone or more systems based upon the establishment of communications withthe system. The immobilizer is configured for seamless operation, and toeffect both data and power communication without necessarily requiringphysical alignment with a base station. Each antenna provides acorresponding communication channel. The immobilizer is configured foroperation on any one of the channels, with a subset of the channels, orall channels (e.g., simultaneously). Energy, data and, in someimplementations, a clock signal are derived from the channels. Where aclock signal is derived, the immobilizer device uses the clock signal tocontrol operation of a communications circuit in the transponder, forcommunicating with the base station.

Upon the introduction of the immobilizer device into a field generatedby the base station, the immobilizer device functions to authenticate orotherwise establish communications between the immobilizer device andthe base station, and is configured to do so using one, two or all threeof the antennas. While a variety of communications protocols and relatedsteps can be implemented, in accordance with various implementations,once the communications have been established/authenticated, additionaldata communications can be effected for operating a system that the basestation is part of (e.g., such as to initiate ignition of anautomobile).

Another example embodiment is directed to an immobilizer device thatcommunicates with a remote base station to permit the operation of acircuit, such as an ignition circuit, connected to the base station.Three orthogonally-oriented antennas are configured to receive wirelesstransmissions from the base station, and to provide a signalcorresponding to the transmissions on a channel, with three suchchannels being provided as corresponding to each of the antennas. Awireless power circuit provides power using signals received from thebase station via at least one of the three antennas. A logic circuit ispowered by the wireless power circuit and processes data signalsreceived from the base station, and generates return communications thatenable operation of the aforesaid circuit (e.g., ignition circuit). Acommunications circuit is also powered by the wireless power circuit,and is connected to the antenna circuit to generate signalscorresponding to the received wireless transmissions on each of theantennas, and provide each generated signal on channel corresponding tothe antenna. Generating such signals may include, for example, using asignal received on one of the channels and synchronizing the delivery ofthe signal with a clock signal. The communications circuit also providesdata communications to the logic circuit, as received from the basestation via at least one of the channels, and transmits data to the basestation via an antenna corresponding to one of the channels.

In a more particular example embodiment, a key fob includes animmobilizer (transponder) that is configured to operate using power froman electromagnetic field provided by a vehicular base station system,such as may be implemented as part of an ignition for an automobile orother vehicle. Power transmission via the electromagnetic field iseffected using, for example, loosely coupled antenna coils configured asresonance circuits. The key fob includes a housing and circuitry forcommunicating information with the vehicle, such as for enabling ordisabling an ignition system. In many implementations, a key fob asdiscussed herein is further configured for operation with a passivekeyless entry system, to facilitate entry to a vehicle (e.g., to unlockthe vehicle's door).

The key fob may further include a battery that can be used to power oneor more aspects of the key fob, which may include power for the use ofthe fob as an ignition component. In this context, the powertransmission facilitated via the electromagnetic field may be used inresponse to loss of battery power, as an alternative to battery power,or in conjunction with battery-powered activity. For example, wherehybrid battery/wireless power is used, battery power can be used if thefob is not positioned within a reliable distance from the base stationthat results in sufficient power transmission to operate the fob. Whensufficient power is derived from the base station, battery power can bebypassed in lieu of power received via the electromagnetic field, topromote battery life. Circuitry within the fob is appropriatelyconfigured to use whichever power source is appropriate. In suchsituations and where applicable, a default power setting is to receivepower via the electromagnetic field, to ensure operation when batteryfailure occurs. Accordingly, the fob can operate independently from thekey fob battery status.

In some implementations, data transmission is effected using, forexample, FSK (frequency shift keying), PSK (phase shift keying) or ASK(amplitude shift keying), such as for communicating data that can beused to unlock or otherwise enable a vehicle's ignition system. Theantennas in the base station and/or the immobilizer may includecylindrical coils or other types of antennas. The coupling between theantennas is enhanced by arranging the antennas relative to one anotherto ensure that an antenna in the immobilizer is on the same general axisposition as an antenna in the base station (to facilitate coaxialoperation). In applications in which the base station antenna area ismuch larger than the transponder antenna, communication (both power anddata) can be effected without precise coaxial operation, but may involvepositioning the axis of one of the transponder antennas close to acenter axis of the base station antenna, with relatively small angulardeviation for desirable operation (e.g., corresponding to a very smalldihedral angle for a range of a few millimeters).

Immobilizers and immobilizer systems as described herein can beimplemented in a variety of manners. In one implementation, animmobilizer includes a base station (transceiver) and a transponderdevice. The immobilizer includes two input pins connected to an antenna.The antenna can be external to the immobilizer, and where appropriate,internal to a key fob in which the immobilizer is implemented. In someimplementations, the antenna includes an LC resonant circuit that useseither discrete components on a PCB or an external coil, and anintegrated capacitor.

The immobilizer also includes a transponder circuit that operates uponan input signal or signals received from a base station, via theantenna. The transponder circuit includes a rectifier or charge pumptype of circuit that generates a supply voltage from the input signal orsignals, and a clock recovery circuit that recreates a clock signal outof an available input signal. The transponder circuit also includes ademodulator (e.g., a comparator) that regenerates a data signalmodulated on the input carrier signal, and modulator that modulates thecarrier signal (e.g., via load modulation) to enable data transmissionback to the base station. A control unit, such as a state machine or aprogrammed microcontroller, and a calculation unit are configured tohandle protocols for operating the immobilizer. A memory device such asa non-volatile memory circuit is used to store data for operation of thetransponder circuit and/or relative functions, such as to storeauthentication-type data usable for enabling an automotive ignition(e.g., without the authentication-type information, the ignition isimmobilized and will not start a vehicle).

Turning now to the Figures, FIG. 1 shows an immobilizer device 110, andimmobilizer system 100, in accordance with other example embodiments ofthe present invention. Various embodiments are directed specifically tothe immobilizer device 110, and other embodiments are directed to theimmobilizer system 100, including the immobilizer device. In addition,various other embodiments are directed to an immobilizer device 110 thatis integrated in a key fob or other device that uses the immobilizerdevice for operation.

The immobilizer device 110 is configured to communicate with a basestation 120 for both data and power transmission. The base station 120includes an antenna 122, represented as a coil by way of example, thatis configured to transmit energy and data (e.g., write data), and toreceive data (e.g., read data) from the immobilizer device 110. On theimmobilizer side of the communications, three antennas 112, 114 and 116are configured for energy and data communication with the antenna 122,and are also represented as coils by way of example.

In addition to the antennas, the immobilizer device 110 includes animmobilizer/transponder chip 130, which has a plurality of transpondercircuits including memory 140, control logic 150 and a calculation unit160. The control logic 150 is further in communication with arectifier/voltage limiter 151, a modulator 152, a clock recovery circuit153, a demodulator 154 and a low frequency (LF) field power on reset(POR) circuit 155, the latter of which can be implemented to ensure atleast a threshold minimum level of power is available for operation. Insome implementations, the POR circuit 155 is configured to detect thefield on a received signal to set a status signal whenever thecorresponding input channel voltage is beyond a certain threshold (e.g.,as described in connection with clock recovery circuits 312, 324 and 334of FIG. 3 below). In some embodiments, a charge pump is used instead ofa rectifier, such as described above.

The immobilizer/transponder chip 130 receives the channel outputs of therespective antennas 112, 114 and 116, and uses one or more of thechannels from which to draw energy from the field generated on coil 122.More particularly, the LF POR circuit 155 generates a reset signal toinitiate operation in response to receiving a communication from thebase station, which effectively indicates that the immobilizer device110 is within a certain distance from the base station 120. Therectifier/voltage limiter 151 generates a supply voltage from the inputsignal or signals, in order to power the chip and/or other components ofthe immobilizer device 110.

The immobilizer/transponder chip 130 also uses one or more of thechannels to obtain data from the base station 120, optionally using thesame channel via which power is received. The clock recovery circuit 153recreates a clock signal using data received from the base station, onone or more channels (and optionally, using a signal channel having thebest signal strength). The demodulator 154 regenerates a data signalmodulated on the input carrier signal, and the signal is provided foruse in the immobilizer device 110.

When the immobilizer/transponder chip 130 is to communicate back to thebase station, the modulator 152 modulates the received signal (e.g., viaload modulation), in order to facilitate data transmission back to thebase station. One or more channels can be modulated simultaneously;where appropriate, a channel exhibiting a highest voltage (and relatedsignal strength) can be used as providing the best signal. The controllogic circuit 150 (e.g., a state machine or a programmedmicrocontroller) and calculation unit 160 are configured to handleprotocols for operating the immobilizer device 110. A memory circuit 140stores data for operation of the transponder device 110 and/or relativefunctions, such as by storing software executed by the control logic150.

FIG. 2 shows an immobilizer and immobilizer system 200 with athree-dimensional antenna system, in accordance with another exampleembodiment of the present invention. The system 200 includes a passivekey fob 210 that communicates with a base station 220, which is part ofand/or communicatively coupled with a system such as a vehicle ignitionsystem. As with the discussion of FIG. 1 above, various embodiments aredirected to the fob 210 alone, and other embodiments are directed to asystem including the base station 220.

The fob 210 includes a low frequency interface circuit 212, a powermanagement circuit 214, and an encryption unit 216. The fob 210 alsoincludes a three-dimensional (3D) immobilizer and low-frequency (LF)receiver circuit 230, which is coupled to three antennas 232, 234 and236. These antennas are arranged orthogonally, and configured such thatone of the antennas is generally aligned with an antenna at the basestation 220, independently from any orientation of the fob 210.

The antennas 232, 234 and 236 provide signals received from the basestation on three separate channels, one for each antenna. The 3Dreceiver circuit 230 is configured to evaluate signals on each of thesechannels for consideration in using the signals for immobilizerfunctions and/or data communications. Such evaluation may involve, forexample, determining a power level, or a modulation index, for eachchannel and selecting one of the channels exhibiting the strongestsignal, or selecting two or more of the channels exhibiting a signalmeeting/exceeding a particular threshold. Such a threshold may bedefined, for example, to suit a particular application and stored as avalue accessible for use in comparing to a value corresponding to thechannel signal strength to determine whether the signal strength of thechannel meets or exceeds the threshold. Accordingly, the fob 210 usessignals on one, two or all three channels for immobilization, dependingupon the implementation. When a signal has been acquired, the fob 210processes two-way link data to ensure secure communications, using theencryption unit 216 as appropriate.

The fob 210 optionally draws power from the signals received on one ormore of the antennas 232, 234 and 236, such as when battery power on thefob 210 is lost and/or otherwise unavailable. The low-frequency (LF)interface circuit 212 and power management circuit 214 operate tocontrol the power received and otherwise interface with the lowfrequency signals received on the antenna(s).

A variety of base stations may be used in connection with theembodiment(s) shown in FIG. 2. In the embodiment exemplified in FIG. 2,base station 220 includes an engine control unit (ECU) 222 and a centralboard computer 224. A low-frequency (LF) communications circuit 250includes an antenna driver 252, and is connected to antennas 254 and256. The antenna 254 generates and receives low-frequency signals, andthe antenna 256 generates a low frequency uplink signal.

Depending upon characteristics of the base station and the fob 210,power may be derived at varied distances. In some implementations, thefob 210 is configured to draw power from the base station 220 (oranother base station) at distances of up to about 10 cm, at voltages onthe antenna of between about 3V and 8V. When battery power is available,the fob 210 is configured to communicate with the base station 220 atranges of up to about 6 m at antenna voltages of between about 100 μVand 5V with a backlink via RF or RF-RF communication, after receiving aLF wakeup signal via the antennas. This high-range battery power may beused, for example, as part of a keyless entry system for a vehicle, inwhich the RF power operation can be used for another function such askeyless entry. For long-range operation, the RF antenna 262 in the basestation 220 (or another base station) may be located at remotelocations, such as in a vehicle's mirrors or roof.

The respective antennas on the fob 210 are all configured to send andreceive low-frequency communications (shown with antenna 254), and toreceive a low-frequency up-link signal (shown coming from antenna 256).Accordingly, the antennas 232, 234 and 236 are all configured to receivepower via a field generated by a base station, and also to communicatewith the base station, under low frequency. By way of example, suchfrequencies as may be applicable to the embodiments shown in FIG. 2 arefrequencies of about 125 kHz. Accordingly, other frequencies are usedfor different applications, such as a frequency in the range of 20 kHzto 150 kHz.

The system 200 is shown as optionally including an RF communicationssystem involving an RF transmitter 240 on the fob 210, and an RFreceiver 260 on the base station 220. The fob 210 is configured togenerate RF communications for communication to the base station 220 viathe RF transmitter 240. In many implementations, the RF communicationssystem is battery-powered, and used for a function that is differentthan that effected via the immobilizer functionality of the 3D receivercircuit 230. For instance, when the fob 210 is used in automotiveapplications, the RF communications circuit can be implemented as akeyless entry function, with the immobilizer functions implemented forvehicle ignition.

In an alternate embodiment, this RF communication is carried out usingpower drawn from the field generated by the base station 220 and/oranother similar base station, and received on the antennas at the fob210 (e.g., once immobilizer functions have been carried out using theantennas 232, 234 and 236. For example, if the RF communications circuitis implemented for battery-powered keyless entry function, and if thebattery fails, a user can position the fob 210 to receive powersufficient to enable vehicular keyless entry RF communications, andagain position the fob 210 to receive power sufficient to enablevehicular ignition functions.

In some implementations, the RF transmitter 240 is an RF transceiverconfigured to both send and receive RF transmissions in bi-directionalcommunications. In these implementations, the low-frequency (LF)receiver function of the 3D receiver circuit 230 may be limited in useto that of a wakeup function, to initiate (e.g., wake up) the passivekey fob 210 from a low-power type of state.

FIG. 3 shows an immobilizer circuit 300, in accordance with anotherexample embodiment of the present invention. The immobilizer circuit 300can be implemented as part of an immobilizer device and/or key fob asdescribed herein, such as shown in FIG. 2 and described above. Threeantenna devices 310, 320 and 330 are shown, each device having anantenna coil, a rectifier and a modulator. These antenna devicesrespectively provide an output channel having sense and limit outputs,with a limit controller 340 connected to the sense output and defining aclamping voltage, and a voltage limiter 350 connected to the limitoutput to limit the input voltage. While a single limiter 350 is shown,other embodiments are directed to implementations in which a separaterectifier is used for each antenna device.

Each of the antenna devices 310, 320 and 330 has corresponding clockrecovery and field detection circuits, respectively including clockrecovery circuits 312, 322 and 332, and field detection circuits 314,324 and 334. The clock recovery circuits 312, 322 and 332 are connectedto a channel selector circuit 360. The field detection circuits 314, 324and 334 check whether the amplitude on the corresponding inputs to whichthey are connected is above a certain threshold. This information isprovided to the channel selector circuit 360, which uses the informationto make a decision as to which clock recovery channel to use as a clocksource for the digital domain (e.g., the input with the highestamplitude may be selected).

A demodulator 370 receives each of the input signals on respectivechannels as provided at antennas of devices 310, 320 and 330. Thedemodulator 370 evaluates the strength of the signals on each channel(e.g., relative to one another), possibly simultaneously, and selectsthe channel providing the strongest signal. In some implementations, thedemodulator 370 evaluates the strength of the channels by selecting achannel exhibiting the highest modulation, relative to the otherchannels. This selected channel is used to provide a demodulated outputfor processing within an immobilizer device.

A modulation circuit 380 provides a modulation signal (MODen) to each ofthe antenna devices derived from either one of the three channels, orfrom a local oscillator reference with the input signal phase of allthree channels individually. In some implementations, the modulationcircuit 380 uses the outputs form the clock recovery circuits 312, 322and 332 (together with an enable signal) to re-synchronize themodulation signal, which can be helpful for avoiding phase jumps duringmodulation and corresponding spikes in the clock signal. The respectiveclock recovery circuits thus facilitate independent clock recovery onall three channels.

Accordingly, as the immobilizer is moved and the respective antennas ondevices 310, 320 and 330 are moved in the field generated by a basedevice, the relative strength of the signals at the antennas can bemonitored and used to select a channel over which communications willtake place. Furthermore, other important functionality such as clocksynchronization, is carried out to maintain a smooth transition as thedevice is oriented differently. In this context, the immobilizer circuit300 checks the signal strength on various signals at an interval thatpermits movement of the fob or other circuit in which the immobilizer isemployed.

FIG. 4 shows another immobilizer and immobilizer system 400 with anotherthree-dimensional antenna system, in accordance with another exampleembodiment of the present invention. The immobilizer system 400 issimilar to the immobilizer system 200 shown in FIG. 2, having adifferent three-dimensional antenna system. Accordingly, components inthe system 400 having reference numbers similar to those in FIG. 2(e.g., 420 and 220) may be implemented in a manner as discussed withFIG. 2 above. As such, detailed description of these components isomitted here for brevity.

Relative to the system 200, the antenna arrangement in the system 400 isarranged such that the individual antennas 432, 434 and 436 share acommon ground, with the other links of each antenna connected to 3Dimmobilizer circuit 430. This approach can be used, for example, withthe system being configured to operate under conditions in which anegative voltage may be present on the input pins, to limit the numberof pins required, which can save space and cost.

Based upon the above discussion and illustrations, those skilled in theart will readily recognize that various modifications and changes may bemade to the present invention without strictly following the exemplaryembodiments and applications illustrated and described herein. Forexample, a variety of different shapes, arrangements and numbers ofantennas can be used to facilitate the communication, to suit particularapplications. One such modification involves the use ofdifferently-arranged antennas. For instance, a transponder as discussedherein may include more than three antennas, with each antenna locatedrelative to the other antennas such that data and power transmissionwith a base station (e.g., as above) are facilitated in a manner thatprovides operability that is generally independent from the orientationof the transponder. Such antennas may be spaced about equally relativeto one another in three dimensional space, or otherwise arranged suchthat a three-dimensional spacing between each antenna and at least oneother antenna is less than such antennas in an orthogonal arrangement.In other implementations, a keyless fob as discussed above is used foran ignition system as well as a keyless entry system, with similarand/or added functionality. Such modifications do not depart from thetrue spirit and scope of the present invention, including that set forthin the following claims.

What is claimed is:
 1. An immobilizer device for communicating with a base station for operation of a circuit connected to the base station, the immobilizer device comprising: an antenna circuit including three antennas orthogonally-oriented relative to one another, each antenna being configured to receive wireless transmissions from a remote base station; a wireless power circuit connected to the antenna circuit and configured to provide power using signals received from the base station via at least one of the three antennas; a communications circuit powered by the wireless power circuit, connected to the antenna circuit and configured to generate signals corresponding to the received wireless transmissions on each of the antennas, and provide each generated signal on a channel corresponding to the antenna, provide data communications received from the base station via at least one of the channels, and transmit data to the base station via an antenna corresponding to one of the channels; and a logic circuit configured to process data communications on at least one of the channels, and to generate a data communication for transmission to the base station using the communications circuit and the one of the antennas corresponding to the at least one of the channels.
 2. The immobilizer device of claim 1, wherein the communications circuit is configured to provide data communications received from the base station via at least one of the channels, by selecting one of the channels exhibiting a signal strength that is higher than the respective signal strengths of the other channels, and providing data communications from the selected channel.
 3. The immobilizer device of claim 1, wherein the communications circuit is configured to provide data communications received from the base station via at least one of the channels, by selecting one of the channels exhibiting a signal strength that exceeds a threshold and providing data communications from the selected channel.
 4. The immobilizer device of claim 1, wherein the communications circuit is configured to transmit data to the base station via an antenna corresponding to one of the channels, by selecting one of the channels exhibiting a signal strength that is higher than the respective signal strengths of the other channels, and transmitting the data generated by the logic circuit via an antenna corresponding to the selected channel.
 5. The immobilizer device of claim 1, wherein the communications circuit is configured to transmit data to the base station via an antenna corresponding to one of the channels, by selecting one of the channels exhibiting a signal strength that exceeds a threshold signal strength, and transmitting the data generated by the logic circuit via an antenna corresponding to the selected channel.
 6. The immobilizer device of claim 1, wherein the communications circuit is further configured to select one of the channels exhibiting a signal strength that is higher than the respective signal strengths of the other channels, provide data communications received from the base station by providing the data communications received via the selected channel, and transmit data to the base station via an antenna corresponding to one of the channels via the antenna corresponding to the selected channel.
 7. The immobilizer device of claim 1, wherein the wireless power circuit is configured to provide power by simultaneously accessing signals received from the base station via at least two of the antennas.
 8. The immobilizer device of claim 1, wherein the wireless power circuit is configured to provide power by simultaneously accessing signals received from the base station via all three of the antennas.
 9. The immobilizer device of claim 1, wherein the communications circuit is configured to provide data communications received on at least two of the channels to the logic circuit for processing.
 10. The immobilizer device of claim 1, wherein the communications circuit is configured to select at least one of the channels exhibiting a threshold signal strength and to use the selected channel to provide a clock signal, and the logic circuit is configured to operate using the provided clock signal.
 11. The immobilizer device of claim 1, wherein the communications circuit is configured to select at least one of the channels exhibiting a higher signal strength, relative to the other channels, and to use the selected channel to provide a clock signal, and the logic circuit is configured to operate using the provided clock signal.
 12. The immobilizer device of claim 1, further including a local oscillator configured to generate a clock signal, and wherein the logic circuit is configured to operate using the generated clock signal.
 13. The immobilizer device of claim 1, wherein the communications circuit includes the logic circuit, and wherein the logic circuit and the communications circuit are configured and arranged to respectively generate and transmit a data communication via the one of the antennas corresponding to the at least one of the channels, using wireless power received via the wireless power circuit, the data communication being configured and arranged to cause the operation of at least one of an ignition circuit and an entry circuit connected to the base station.
 14. The immobilizer device of claim 1, wherein the communications circuit is configured to communicate with the base station using a low-frequency signal in a range of between about 20 kHz and 150 kHz.
 15. The immobilizer device of claim 1, further including a clock generation circuit configured to generate a clock signal using a clock signal on one of the channels exhibiting a higher strength, relative to the other channels, regenerate a clock signal by re-evaluating the signal strength of all of the channels, and using one of the channels exhibiting a higher strength, relative to the other channels, from which to derive a clock recovery signal, and use the clock recovery signal to resynchronize the provided data communications received from the base station.
 16. An immobilizer key fob device for communicating with a base station for an automobile ignition circuit that requires data from the immobilizer to operate, the immobilizer key fob device comprising: an antenna circuit having three orthogonally-oriented antennas that respectively generate input signals on three different antenna channels, and configured and arranged to align with a field generated by a single-antenna in the base station for receiving RF communications from the base station; a power circuit configured to generate a supply voltage using an input radio frequency (RF) signal received from the base station on at least one of the antennas; a demodulator circuit configured to select one of the channels based upon a strength of a signal communicated thereupon, and to provide a data signal from the selected channel for processing; a modulator circuit configured to modulate a carrier signal for data transmission back to the base station; a memory circuit configured to store authentication data and program data; and a logic circuit configured to execute the program data in the memory circuit to process data received via the antenna circuit and demodulator circuit, and to generate output data for communication back to the base station via the modulator circuit and antennal circuit, using the authentication data.
 17. The device of claim 16, wherein the antennas in the antenna circuit are configured and arranged to receive an RF signal from the base station that is sufficient to power the immobilizer key fob device and to pass RF communications between the immobilizer key fob device and the base station, independently from the orientation of the immobilizer key fob device.
 18. The device of claim 16, wherein the demodulator circuit is configured to monitor the strength of the signals on each of the channels and, in response to one of the signals on another one of the channels that is not the selected channel overtaking the signal strength of the signal on the selected channel, provide the data signal from the other one of the channels.
 19. The device of claim 16, further including a clock generation circuit configured to generate a clock signal using an input signal received on one of the antenna channels, and synchronize the provided data signal using the clock signal, and re-generate the clock signal by evaluating the strength of the signals on each of the channels and using the signal from the channel exhibiting the highest signal strength to re-generate the clock signal.
 20. A method for implementation at an immobilizer circuit for communicating with a remote base station using RF power, the method comprising: using an antenna circuit having three antennas orthogonally-oriented relative to one another, receiving wireless transmissions from the base station; using the wireless transmissions received on the antenna circuit from the base station to generate power to power a logic circuit; generating signals corresponding to the received wireless transmissions on each of the antennas, and providing each generated signal on a channel corresponding to the antenna; providing data communications received from the base station via at least one of the channels to the logic circuit; in the logic circuit, processing data communications received on at least one of the channels, generating a data communication for transmission to the base station using the communications circuit and the one of the antennas corresponding to the at least one of the channels; and transmitting the generated data communication to the base station via an antenna corresponding to one of the channels. 